The present invention relates to controlling the supply of power to a portable communication device of the type mentioned in the preamble of the independent claims.
Many portable communication devices, such as mobile telephones, personal communicators etc, normally require a xe2x80x9chardware power on systemxe2x80x9d for powering on. A xe2x80x9chardware power on systemxe2x80x9d is referred to as a system, which comprises a physical switch, controlling the power on of the portable communication device.
Other portable communication devices have a hinged front panel, a so-called a flip, which can be opened when the device is used for certain functions and which can be closed in order to reduce the bulk of the device when these functions are not required.
One example of such a device is the mobile telephone known from the patent GB-A-2 297 661 which has a flip which can be folded down to expose a touch screen display. When the flip is folded up against the touch screen display the screen can be operated by means of a keypad consisting of a plurality of buttons which extend through the flip and which can be pressed by a user into contact with the touch sensitive parts of the touch screen display. There is a flip position-indicating switch in the main body of the unit which can be operated by a switch activation device disposed in the flip. The flip position indicating switch and switch activation device co-operate to produce a mode change signal which is sent to the processor of the mobile phone and which indicates if the flip is open or closed. If the flip is closed a first set of functions is available to the user and if the flip is open a second set of functions is available to the user. Cellular telephones of this type can be switched on and off by a hardware switch which disconnects tie processor from the logic voltage supply in order to minimise unnecessary battery drainage caused by the logic voltage supply leakage current.
Thus a separate hardware switch is required which increases the manufacturing costs and, as it introduces a potential failure path, and also lowers the reliability of the mobile telephone.
It is also known to use xe2x80x9csoft power controlxe2x80x9d for instance in personal computer systems, to be able to save power and extend battery lifetime. This is ordinarily done by the operator of the computer system powering on not using a xe2x80x9chard power on switchxe2x80x9d. xe2x80x9cSoft power controlxe2x80x9d in such a computer system normally comprise several power control modes, such as a xe2x80x9cfull power modexe2x80x9d and a sleep mode. In the xe2x80x9cfull power modexe2x80x9d, the main parts of the computer system are supplied with power and are active. In the xe2x80x9csleep modexe2x80x9d, one or more parts of the computer system are not supplied with power and are said to be inactive. In the xe2x80x9csleep modexe2x80x9d, the operator depresses a key on the keyboard to power on the main parts of the computer system.
It is known from U.S. Pat. No. 5,553,296 to use a touch screen for a power control function in a computer system, whereby the touch screen is employed to control a number of power modes, such as xe2x80x9cfull power modexe2x80x9d and xe2x80x9csleep modexe2x80x9d in the computer system. The touch screen detects a touch input by the operator from the touch screen. If the computer system is in a power down mode, a so-called xe2x80x9csleep modexe2x80x9d, the touch screen provides a main power on signal after the touch is detected.
U.S. Pat. No. 4,825,209 describes a remote control apparatus, which puts a transmitting portion, a receiving portion and an image display control portion thereof in an enabled state for a predetermined period of time after a touch panel is pressed to reduce power consumption. The press detection is done with push button switches in the corners of a remote control.
JP-A-8-212 006 describes switching on a flat panel indicator if any touch input is sensed. When there is no touch input for a predetermined time period, the flat panel is switched off.
One problem is that prior art portable communication devices, such as a mobile phone comprising a touch screen display, such as a touch screen LCD (Liquid Crystal Display), require additional mechanical on-off switches positioned at different locations, whereby the way to power up differs from device to device, even for similar devices of the same family.
Another problem is that these switches require space to be implemented in the portable communication devices.
Yet another problem is that today""s portable communication devices, in particular portable telephones comprising a flip hang, must be provided with wires through the flip hinge if a hardware power on-off switch is provided thereon.
The object of the invention is to solve the described problems and provide an improved portable telephone, in which the use of a separate hardware switch to switch on the device is unnecessary. Herein, portable telephones means: mobile telephones, cordless telephones and personal communicators.
Another object of the present invention is to improve the reliability of such a portable telephone and to reduce their manufacturing costs.
This is attained according to the present invention by means of a portable telephone in which the touch screen display is used for switching on the device, wherein a hardware switch is unnecessary. The touch screen display comprises at least one inner and one outer essentially transparent conducting plate which are movable in relation to each other between a first position, in which the plates are spaced apart and a second position, in which the plates are contacted to each other by the outer plate being depressed by a user of the portable telephone by means of an input means, such as a key pad or direct activation providing a pressure against the touch screen display, wherein a voltage controlled switch connected to said plates is adapted to turn on the power of the portable telephone upon receipt of a signal indicating that a power-on key has been depressed by the user.
An advantage of the present invention is that the invention simplifies the use of a portable telephone, compared to known technique.
Another advantage of the present invention is that no additional switch must be incorporated in the portable telephone. It is possible to use the image display of a portable telephone, independent on model for powering on.
The invention will now be described in more detail with reference to preferred embodiments and to the appended drawings.